import Barrett from './barret';
import Classic from './classic';
import Montgomery from './montgomery';
import NullExp from './null-exp';
import SecureRandom from './secure-random';

// Basic JavaScript BN library - subset useful for RSA encryption.

// JavaScript engine analysis
const canary = 0xdeadbeefcafe;
const j_lm = ((canary & 0xffffff) === 0xefcafe);
const BI_FP = 52;

const lowprimes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997];
const lplim = (1 << 26) / lowprimes[lowprimes.length - 1];

// BigInteger interfaces not implemented in jsbn:

// BigInteger(int signum, byte[] magnitude)
// double doubleValue()
// float floatValue()
// int hashCode()
// long longValue()
// static BigInteger valueOf(long val)

// am1: use a single mult and divide to get the high bits,
// max digit bits should be 26 because
// max internal value = 2*dvalue^2-2*dvalue (< 2^53)
function am1(this: BigInteger, i: number, x: number, w: BigInteger, j: number, c: number, n: number) {
	while (--n >= 0) {
		const v = x * this[i++] + w[j] + c;
		c = Math.floor(v / 0x4000000);
		w[j++] = v & 0x3ffffff;
	}
	return c;
}

// am2 avoids a big mult-and-extract completely.
// Max digit bits should be <= 30 because we do bitwise ops
// on values up to 2*hdvalue^2-hdvalue-1 (< 2^31)
function am2(this: BigInteger, i: number, x: number, w: BigInteger, j: number, c: number, n: number) {
	const xl = x & 0x7fff;
	const xh = x >> 15;
	while (--n >= 0) {
		let l = this[i] & 0x7fff;
		const h = this[i++] >> 15;
		const m = xh * l + h * xl;
		l = xl * l + ((m & 0x7fff) << 15) + w[j] + (c & 0x3fffffff);
		c = (l >>> 30) + (m >>> 15) + xh * h + (c >>> 30);
		w[j++] = l & 0x3fffffff;
	}
	return c;
}

// Alternately, set max digit bits to 28 since some
// browsers slow down when dealing with 32-bit numbers.
function am3(this: BigInteger, i: number, x: number, w: BigInteger, j: number, c: number, n: number) {
	const xl = x & 0x3fff;
	const xh = x >> 14;
	while (--n >= 0) {
		let l = this[i] & 0x3fff;
		const h = this[i++] >> 14;
		const m = xh * l + h * xl;
		l = xl * l + ((m & 0x3fff) << 14) + w[j] + c;
		c = (l >> 28) + (m >> 14) + xh * h;
		w[j++] = l & 0xfffffff;
	}
	return c;
}

// Bits per digit
const { am, dbits } = (() => {
	// am: Compute w_j += (x*this_i), propagate carries,
	// c is initial carry, returns final carry.
	// c < 3*dvalue, x < 2*dvalue, this_i < dvalue
	// We need to select the fastest one that works in this environment.
	const inBrowser = typeof navigator !== 'undefined';
	if (inBrowser && j_lm && (navigator.appName === 'Microsoft Internet Explorer')) {
		return {
			am: am2,
			dbits: 30
		};
	} else if (inBrowser && j_lm && (navigator.appName !== 'Netscape')) {
		return {
			am: am1,
			dbits: 26
		};
	} else { // Mozilla/Netscape seems to prefer am3
		return {
			am: am3,
			dbits: 28
		};
	}
})();

export default class BigInteger {
	// "constants"
	public static ZERO = nbv(0);
	public static ONE = nbv(1);

	public Barrett = Barrett;

	public am = am;
	public s = 0;
	public t = 0;
	public DB = dbits;
	public DM = ((1 << dbits) - 1);
	public DV = (1 << dbits);

	protected FV = Math.pow(2, BI_FP);
	protected F1 = BI_FP - dbits;
	protected F2 = 2 * dbits - BI_FP;
	constructor(a?: string | number | null, b?: number | SecureRandom, c?: number) {
		if (a !== null && a !== undefined) {
			if ('number' === typeof a) {
				this.fromNumber(a, b!, c);
			} else if (b === null && 'string' !== typeof a) {
				this.fromString(a, 256);
			} else {
				this.fromString(a, b as number);
			}
		}
	}


	// (public) return string representation in given radix
	public toString(b?: 2 | 4 | 8 | 16 | 32): string {
		if (this.s < 0) {
			return '-' + this.negate().toString(b);
		}
		let k;
		if (b === 16) {
			k = 4;
		} else if (b === 8) {
			k = 3;
		} else if (b === 2) {
			k = 1;
		} else if (b === 32) {
			k = 5;
		} else if (b === 4) {
			k = 2;
		} else {
			return this.toRadix(b);
		}
		const km = (1 << k) - 1;
		let d;
		let m = false;
		let r = '';
		let i = this.t;
		let p = this.DB - (i * this.DB) % k;
		if (i-- > 0) {
			// tslint:disable-next-line:no-conditional-assignment
			if (p < this.DB && (d = this[i] >> p) > 0) { m = true; r = int2char(d); }
			while (i >= 0) {
				if (p < k) {
					d = (this[i] & ((1 << p) - 1)) << (k - p);
					d |= this[--i] >> (p += this.DB - k);
				} else {
					d = (this[i] >> (p -= k)) & km;
					if (p <= 0) { p += this.DB; --i; }
				}
				if (d > 0) {
					m = true;
				}
				if (m) {
					r += int2char(d);
				}
			}
		}
		return m ? r : '0';
	}

	// (public) -this
	public negate() {
		const r = nbi(); BigInteger.ZERO.subTo(this, r); return r;
	}

	// (public) |this|
	public abs() {
		return (this.s < 0) ? this.negate() : this;
	}

	// (public) return + if this > a, - if this < a, 0 if equal
	public compareTo(a: BigInteger) {
		let r = this.s - a.s;
		if (r !== 0) {
			return r;
		}
		let i = this.t;
		r = i - a.t;
		if (r !== 0) {
			return (this.s < 0) ? -r : r;
		}
		while (--i >= 0) {
			// tslint:disable-next-line:no-conditional-assignment
			if ((r = this[i] - a[i]) !== 0) {
				return r;
			}
		}
		return 0;
	}

	// (public) return the number of bits in "this"
	public bitLength() {
		if (this.t <= 0) {
			return 0;
		}
		return this.DB * (this.t - 1) + nbits(this[this.t - 1] ^ (this.s & this.DM));
	}


	// (public) this mod a
	public mod(a: BigInteger) {
		const r = nbi();
		this.abs().divRemTo(a, null, r);
		if (this.s < 0 && r.compareTo(BigInteger.ZERO) > 0) {
			a.subTo(r, r);
		}
		return r;
	}

	// (public) this^e % m, 0 <= e < 2^32
	public modPowInt(e: number, m: BigInteger) {
		let z;
		if (e < 256 || m.isEven()) {
			z = new Classic(m);
		} else {
			z = new Montgomery(m);
		}
		return this.exp(e, z);
	}

	// (protected) set from integer value x, -DV <= x < DV
	public fromInt(x: number) {
		this.t = 1;
		this.s = (x < 0) ? -1 : 0;
		if (x > 0) {
			this[0] = x;
		} else if (x < -1) {
			this[0] = x + this.DV;
		} else {
			this.t = 0;
		}
	}

	// (protected) divide this by m, quotient and remainder to q, r (HAC 14.20)
	// r != q, this != m.  q or r may be null.
	public divRemTo(m: BigInteger, q: BigInteger | null, r: BigInteger | null) {
		const pm = m.abs();
		if (pm.t <= 0) { return; }
		const pt = this.abs();
		if (pt.t < pm.t) {
			if (q != null) { q.fromInt(0); }
			if (r != null) { this.copyTo(r); }
			return;
		}
		if (r == null) { r = nbi(); }
		const y = nbi();
		const ts = this.s;
		const ms = m.s;
		const nsh = this.DB - nbits(pm[pm.t - 1]);   // normalize modulus
		if (nsh > 0) { pm.lShiftTo(nsh, y); pt.lShiftTo(nsh, r); } else { pm.copyTo(y); pt.copyTo(r); }
		const ys = y.t;
		const y0 = y[ys - 1];
		if (y0 === 0) { return; }
		const yt = y0 * (1 << this.F1) + ((ys > 1) ? y[ys - 2] >> this.F2 : 0);
		const d1 = this.FV / yt;
		const d2 = (1 << this.F1) / yt;
		const e = 1 << this.F2;
		let i = r.t;
		let j = i - ys;
		const t = (q == null) ? nbi() : q;
		y.dlShiftTo(j, t);
		if (r.compareTo(t) >= 0) {
			r[r.t++] = 1;
			r.subTo(t, r);
		}
		BigInteger.ONE.dlShiftTo(ys, t);
		t.subTo(y, y);  // "negative" y so we can replace sub with am later
		while (y.t < ys) { y[y.t++] = 0; }
		while (--j >= 0) {
			// Estimate quotient digit
			let qd = (r[--i] === y0) ? this.DM : Math.floor(r[i] * d1 + (r[i - 1] + e) * d2);
			// tslint:disable-next-line:no-conditional-assignment
			if ((r[i] += y.am(0, qd, r, j, 0, ys)) < qd) {   // Try it out
				y.dlShiftTo(j, t);
				r.subTo(t, r);
				while (r[i] < --qd) { r.subTo(t, r); }
			}
		}
		if (q != null) {
			r.drShiftTo(ys, q);
			if (ts !== ms) { BigInteger.ZERO.subTo(q, q); }
		}
		r.t = ys;
		r.clamp();
		if (nsh > 0) { r.rShiftTo(nsh, r); } // Denormalize remainder
		if (ts < 0) { BigInteger.ZERO.subTo(r, r); }
	}

	// (protected) r = this * a, r != this,a (HAC 14.12)
	// "this" should be the larger one if appropriate.
	public multiplyTo(a: BigInteger, r: BigInteger) {
		const x = this.abs();
		const y = a.abs();
		let i = x.t;
		r.t = i + y.t;
		while (--i >= 0) {
			r[i] = 0;
		}
		for (i = 0; i < y.t; ++i) {
			r[i + x.t] = x.am(0, y[i], r, i, 0, x.t);
		}
		r.s = 0;
		r.clamp();
		if (this.s !== a.s) {
			BigInteger.ZERO.subTo(r, r);
		}
	}


	// (protected) r = this^2, r != this (HAC 14.16)
	public squareTo(r: BigInteger) {
		const x = this.abs();
		let i = r.t = 2 * x.t;
		while (--i >= 0) { r[i] = 0; }
		for (i = 0; i < x.t - 1; ++i) {
			const c = x.am(i, x[i], r, 2 * i, 0, 1);
			// tslint:disable-next-line:no-conditional-assignment
			if ((r[i + x.t] += x.am(i + 1, 2 * x[i], r, 2 * i + 1, c, x.t - i - 1)) >= x.DV) {
				r[i + x.t] -= x.DV;
				r[i + x.t + 1] = 1;
			}
		}
		if (r.t > 0) { r[r.t - 1] += x.am(i, x[i], r, 2 * i, 0, 1); }
		r.s = 0;
		r.clamp();
	}


	// (protected) return "-1/this % 2^DB"; useful for Mont. reduction
	// justification:
	//         xy == 1 (mod m)
	//         xy =  1+km
	//   xy(2-xy) = (1+km)(1-km)
	// x[y(2-xy)] = 1-k^2m^2
	// x[y(2-xy)] == 1 (mod m^2)
	// if y is 1/x mod m, then y(2-xy) is 1/x mod m^2
	// should reduce x and y(2-xy) by m^2 at each step to keep size bounded.
	// JS multiply "overflows" differently from C/C++, so care is needed here.
	public invDigit() {
		if (this.t < 1) {
			return 0;
		}
		const x = this[0];
		if ((x & 1) === 0) {
			return 0;
		}
		let y = x & 3;       // y == 1/x mod 2^2
		y = (y * (2 - (x & 0xf) * y)) & 0xf; // y == 1/x mod 2^4
		y = (y * (2 - (x & 0xff) * y)) & 0xff;   // y == 1/x mod 2^8
		y = (y * (2 - (((x & 0xffff) * y) & 0xffff))) & 0xffff;    // y == 1/x mod 2^16
		// last step - calculate inverse mod DV directly;
		// assumes 16 < DB <= 32 and assumes ability to handle 48-bit ints
		y = (y * (2 - x * y % this.DV)) % this.DV;       // y == 1/x mod 2^dbits
		// we really want the negative inverse, and -DV < y < DV
		return (y > 0) ? this.DV - y : -y;
	}

	// (protected) r = this - a
	public subTo(a: BigInteger, r: BigInteger) {
		let i = 0;
		let c = 0;
		const m = Math.min(a.t, this.t);
		while (i < m) {
			c += this[i] - a[i];
			r[i++] = c & this.DM;
			c >>= this.DB;
		}
		if (a.t < this.t) {
			c -= a.s;
			while (i < this.t) {
				c += this[i];
				r[i++] = c & this.DM;
				c >>= this.DB;
			}
			c += this.s;
		} else {
			c += this.s;
			while (i < a.t) {
				c -= a[i];
				r[i++] = c & this.DM;
				c >>= this.DB;
			}
			c -= a.s;
		}
		r.s = (c < 0) ? -1 : 0;
		if (c < -1) { r[i++] = this.DV + c; } else if (c > 0) { r[i++] = c; }
		r.t = i;
		r.clamp();
	}

	// (protected) r = this << n*DB
	public dlShiftTo(n: number, r: BigInteger) {
		let i;
		for (i = this.t - 1; i >= 0; --i) {
			r[i + n] = this[i];
		}
		for (i = n - 1; i >= 0; --i) {
			r[i] = 0;
		}
		r.t = this.t + n;
		r.s = this.s;
	}

	// (protected) clamp off excess high words
	public clamp() {
		const c = this.s & this.DM;
		while (this.t > 0 && this[this.t - 1] === c) {
			--this.t;
		}
	}

	// (protected) r = this >> n*DB
	public drShiftTo(n: number, r: BigInteger) {
		for (let i = n; i < this.t; ++i) {
			r[i - n] = this[i];
		}
		r.t = Math.max(this.t - n, 0);
		r.s = this.s;
	}

	// Extended JavaScript BN functions, required for RSA private ops.

	// Version 1.1: new BigInteger("0", 10) returns "proper" zero
	// Version 1.2: square() API, isProbablePrime fix

	// (public)
	public clone() {
		const r = nbi();
		this.copyTo(r);
		return r;
	}

	// (public) 0 if this == 0, 1 if this > 0
	public signum() {
		if (this.s < 0) {
			return -1;
		} else if (this.t <= 0 || (this.t === 1 && this[0] <= 0)) {
			return 0;
		} else {
			return 1;
		}
	}

	// (public) return value as integer
	public intValue() {
		if (this.s < 0) {
			if (this.t === 1) { return this[0] - this.DV; } else if (this.t === 0) { return -1; }
		} else if (this.t === 1) { return this[0]; } else if (this.t === 0) { return 0; }
		// assumes 16 < DB < 32
		return ((this[1] & ((1 << (32 - this.DB)) - 1)) << this.DB) | this[0];
	}

	// (public) true iff nth bit is set
	public testBit(n: number) {
		const j = Math.floor(n / this.DB);
		if (j >= this.t) {
			return (this.s !== 0);
		}
		return ((this[j] & (1 << (n % this.DB))) !== 0);
	}

	// (public) this << n
	public shiftLeft(n: number) {
		const r = nbi();
		if (n < 0) { this.rShiftTo(-n, r); } else { this.lShiftTo(n, r); }
		return r;
	}

	// (public) test primality with certainty >= 1-.5^t
	public isProbablePrime(t: number) {
		let i;
		const x = this.abs();
		if (x.t === 1 && x[0] <= lowprimes[lowprimes.length - 1]) {
			for (i = 0; i < lowprimes.length; ++i) {
				if (x[0] === lowprimes[i]) { return true; }
			}
			return false;
		}
		if (x.isEven()) { return false; }
		i = 1;
		while (i < lowprimes.length) {
			let m = lowprimes[i];
			let j = i + 1;
			while (j < lowprimes.length && m < lplim) {
				m *= lowprimes[j++];
			}
			m = x.modInt(m);
			while (i < j) { if (m % lowprimes[i++] === 0) { return false; } }
		}
		return x.millerRabin(t);
	}

	// (public) this - a
	public subtract(a: BigInteger) {
		const r = nbi();
		this.subTo(a, r);
		return r;
	}

	// (public) returns index of lowest 1-bit (or -1 if none)
	public getLowestSetBit() {
		for (let i = 0; i < this.t; ++i) {
			if (this[i] !== 0) {
				return i * this.DB + lbit(this[i]);
			}
		}
		if (this.s < 0) {
			return this.t * this.DB;
		}
		return -1;
	}

	// (public) this >> n
	public shiftRight(n: number) {
		const r = nbi();
		if (n < 0) {
			this.lShiftTo(-n, r);
		} else {
			this.rShiftTo(n, r);
		}
		return r;
	}

	// (public) this^e % m (HAC 14.85)
	public modPow(e: BigInteger, m: BigInteger) {
		let i = e.bitLength();
		let k;
		let r = nbv(1);
		let z;
		if (i <= 0) { return r; } else if (i < 18) { k = 1; } else if (i < 48) { k = 3; } else if (i < 144) { k = 4; } else if (i < 768) { k = 5; } else { k = 6; }
		if (i < 8) {
			z = new Classic(m);
		} else if (m.isEven()) {
			z = new Barrett(m);
		} else {
			z = new Montgomery(m);
		}

		// precomputation
		const g = new Array();
		let n = 3;
		const k1 = k - 1;
		const km = (1 << k) - 1;
		g[1] = z.convert(this);
		if (k > 1) {
			const g2 = nbi();
			z.sqrTo(g[1], g2);
			while (n <= km) {
				g[n] = nbi();
				z.mulTo(g2, g[n - 2], g[n]);
				n += 2;
			}
		}

		let j = e.t - 1;
		let w;
		let is1 = true;
		let r2 = nbi();
		let t;
		i = nbits(e[j]) - 1;
		while (j >= 0) {
			if (i >= k1) { w = (e[j] >> (i - k1)) & km; } else {
				w = (e[j] & ((1 << (i + 1)) - 1)) << (k1 - i);
				if (j > 0) { w |= e[j - 1] >> (this.DB + i - k1); }
			}

			n = k;
			while ((w & 1) === 0) { w >>= 1; --n; }
			// tslint:disable-next-line:no-conditional-assignment
			if ((i -= n) < 0) { i += this.DB; --j; }
			if (is1) {    // ret == 1, don't bother squaring or multiplying it
				g[w].copyTo(r);
				is1 = false;
			} else {
				while (n > 1) { z.sqrTo(r, r2); z.sqrTo(r2, r); n -= 2; }
				if (n > 0) { z.sqrTo(r, r2); } else { t = r; r = r2; r2 = t; }
				z.mulTo(r2, g[w], r);
			}

			while (j >= 0 && (e[j] & (1 << i)) === 0) {
				z.sqrTo(r, r2); t = r; r = r2; r2 = t;
				if (--i < 0) { i = this.DB - 1; --j; }
			}
		}
		return z.revert(r);
	}

	// (public) this / a
	public divide(a: BigInteger) {
		const r = nbi();
		this.divRemTo(a, r, null);
		return r;
	}

	// (protected) copy this to r
	public copyTo(r: BigInteger) {
		for (let i = this.t - 1; i >= 0; --i) {
			r[i] = this[i];
		}
		r.t = this.t;
		r.s = this.s;
	}

	// (public) return value as byte
	public byteValue() {
		return (this.t === 0) ? this.s : (this[0] << 24) >> 24;
	}

	// (public) return value as short (assumes DB>=16)
	public shortValue() {
		return (this.t === 0) ? this.s : (this[0] << 16) >> 16;
	}

	// (public) convert to bigendian byte array
	public toByteArray() {
		let i = this.t;
		const r = new Array();
		r[0] = this.s;
		let p = this.DB - (i * this.DB) % 8;
		let d;
		let k = 0;
		if (i-- > 0) {
			// tslint:disable-next-line:no-conditional-assignment
			if (p < this.DB && (d = this[i] >> p) !== (this.s & this.DM) >> p) {
				r[k++] = d | (this.s << (this.DB - p));
			}
			while (i >= 0) {
				if (p < 8) {
					d = (this[i] & ((1 << p) - 1)) << (8 - p);
					d |= this[--i] >> (p += this.DB - 8);
				} else {
					d = (this[i] >> (p -= 8)) & 0xff;
					if (p <= 0) { p += this.DB; --i; }
				}
				if ((d & 0x80) !== 0) { d |= -256; }
				if (k === 0 && (this.s & 0x80) !== (d & 0x80)) { ++k; }
				if (k > 0 || d !== this.s) { r[k++] = d; }
			}
		}
		return r;
	}

	public equals(a: BigInteger) {
		return (this.compareTo(a) === 0);
	}

	public min(a: BigInteger) {
		return (this.compareTo(a) < 0) ? this : a;
	}

	public max(a: BigInteger) {
		return (this.compareTo(a) > 0) ? this : a;
	}
	public and(a: BigInteger) {
		const r = nbi();
		this.bitwiseTo(a, op_and, r);
		return r;
	}
	// (public) this | a
	public or(a: BigInteger) {
		const r = nbi();
		this.bitwiseTo(a, op_or, r);
		return r;
	}
	public xor(a: BigInteger) {
		const r = nbi();
		this.bitwiseTo(a, op_xor, r);
		return r;
	}

	public andNot(a: BigInteger) {
		const r = nbi();
		this.bitwiseTo(a, op_andnot, r);
		return r;
	}

	// (public) ~this
	public not() {
		const r = nbi();
		for (let i = 0; i < this.t; ++i) {
			r[i] = this.DM & ~this[i];
		}
		r.t = this.t;
		r.s = ~this.s;
		return r;
	}

	// (public) return number of set bits
	public bitCount() {
		let r = 0;
		const x = this.s & this.DM;
		for (let i = 0; i < this.t; ++i) { r += cbit(this[i] ^ x); }
		return r;
	}


	// (public) this | (1<<n)
	public setBit(n: number) {
		return this.changeBit(n, op_or);
	}

	// (public) this & ~(1<<n)
	public clearBit(n: number) {
		return this.changeBit(n, op_andnot);
	}

	// (public) this ^ (1<<n)
	public flipBit(n: number) {
		return this.changeBit(n, op_xor);
	}

	// (public) this + a
	public add(a: BigInteger) {
		const r = nbi();
		this.addTo(a, r);
		return r;
	}

	// (public) this * a
	public multiply(a: BigInteger) {
		const r = nbi();
		this.multiplyTo(a, r);
		return r;
	}

	// (public) this^2
	public square() {
		const r = nbi();
		this.squareTo(r);
		return r;
	}

	// (public) this % a
	public remainder(a: BigInteger) {
		const r = nbi();
		this.divRemTo(a, null, r);
		return r;
	}

	// (public) [this/a,this%a]
	public divideAndRemainder(a: BigInteger) {
		const q = nbi();
		const r = nbi();
		this.divRemTo(a, q, r);
		return new Array(q, r);
	}

	// (public) this^e
	public pow(e: number) {
		return this.exp(e, new NullExp());
	}

	// (public) gcd(this,a) (HAC 14.54)
	public gcd(a: BigInteger) {
		let x = (this.s < 0) ? this.negate() : this.clone();
		let y = (a.s < 0) ? a.negate() : a.clone();
		if (x.compareTo(y) < 0) {
			const t = x;
			x = y;
			y = t;
		}
		let i = x.getLowestSetBit();
		let g = y.getLowestSetBit();
		if (g < 0) { return x; }
		if (i < g) { g = i; }
		if (g > 0) {
			x.rShiftTo(g, x);
			y.rShiftTo(g, y);
		}
		while (x.signum() > 0) {
			// tslint:disable-next-line:no-conditional-assignment
			if ((i = x.getLowestSetBit()) > 0) { x.rShiftTo(i, x); }
			// tslint:disable-next-line:no-conditional-assignment
			if ((i = y.getLowestSetBit()) > 0) { y.rShiftTo(i, y); }
			if (x.compareTo(y) >= 0) {
				x.subTo(y, x);
				x.rShiftTo(1, x);
			} else {
				y.subTo(x, y);
				y.rShiftTo(1, y);
			}
		}
		if (g > 0) { y.lShiftTo(g, y); }
		return y;
	}

	// (public) 1/this % m (HAC 14.61)
	public modInverse(m: BigInteger) {
		const ac = m.isEven();
		if ((this.isEven() && ac) || m.signum() === 0) { return BigInteger.ZERO; }
		const u = m.clone();
		const v = this.clone();
		const a = nbv(1);
		const b = nbv(0);
		const c = nbv(0);
		const d = nbv(1);
		while (u.signum() !== 0) {
			while (u.isEven()) {
				u.rShiftTo(1, u);
				if (ac) {
					if (!a.isEven() || !b.isEven()) { a.addTo(this, a); b.subTo(m, b); }
					a.rShiftTo(1, a);
				} else if (!b.isEven()) { b.subTo(m, b); }
				b.rShiftTo(1, b);
			}
			while (v.isEven()) {
				v.rShiftTo(1, v);
				if (ac) {
					if (!c.isEven() || !d.isEven()) { c.addTo(this, c); d.subTo(m, d); }
					c.rShiftTo(1, c);
				} else if (!d.isEven()) { d.subTo(m, d); }
				d.rShiftTo(1, d);
			}
			if (u.compareTo(v) >= 0) {
				u.subTo(v, u);
				if (ac) { a.subTo(c, a); }
				b.subTo(d, b);
			} else {
				v.subTo(u, v);
				if (ac) { c.subTo(a, c); }
				d.subTo(b, d);
			}
		}
		if (v.compareTo(BigInteger.ONE) !== 0) { return BigInteger.ZERO; }
		if (d.compareTo(m) >= 0) { return d.subtract(m); }
		if (d.signum() < 0) { d.addTo(m, d); } else { return d; }
		if (d.signum() < 0) { return d.add(m); } else { return d; }
	}

	// (protected) r = "this * a" without lower n words, n > 0
	// "this" should be the larger one if appropriate.
	public multiplyUpperTo(a: BigInteger, n: number, r: BigInteger) {
		--n;
		let i = r.t = this.t + a.t - n;
		r.s = 0; // assumes a,this >= 0
		while (--i >= 0) {
			r[i] = 0;
		}
		for (i = Math.max(n - this.t, 0); i < a.t; ++i) {
			r[this.t + i - n] = this.am(n - i, a[i], r, 0, 0, this.t + i - n);
		}
		r.clamp();
		r.drShiftTo(1, r);
	}

	// (protected) r = lower n words of "this * a", a.t <= n
	// "this" should be the larger one if appropriate.
	public multiplyLowerTo(a: BigInteger, n: number, r: BigInteger) {
		let i = Math.min(this.t + a.t, n);
		r.s = 0; // assumes a,this >= 0
		r.t = i;
		while (i > 0) {
			r[--i] = 0;
		}
		let j;
		for (j = r.t - this.t; i < j; ++i) { r[i + this.t] = this.am(0, a[i], r, i, 0, this.t); }
		for (j = Math.min(a.t, n); i < j; ++i) { this.am(0, a[i], r, i, 0, n - i); }
		r.clamp();
	}

	// (protected) this += n << w words, this >= 0
	public dAddOffset(n: number, w: number) {
		if (n === 0) {
			return;
		}
		while (this.t <= w) {
			this[this.t++] = 0;
		}
		this[w] += n;
		while (this[w] >= this.DV) {
			this[w] -= this.DV;
			if (++w >= this.t) { this[this.t++] = 0; }
			++this[w];
		}
	}

	// (protected) r = this + a
	protected addTo(a: BigInteger, r: BigInteger) {
		let i = 0;
		let c = 0;
		const m = Math.min(a.t, this.t);
		while (i < m) {
			c += this[i] + a[i];
			r[i++] = c & this.DM;
			c >>= this.DB;
		}
		if (a.t < this.t) {
			c += a.s;
			while (i < this.t) {
				c += this[i];
				r[i++] = c & this.DM;
				c >>= this.DB;
			}
			c += this.s;
		} else {
			c += this.s;
			while (i < a.t) {
				c += a[i];
				r[i++] = c & this.DM;
				c >>= this.DB;
			}
			c += a.s;
		}
		r.s = (c < 0) ? -1 : 0;
		if (c > 0) { r[i++] = c; } else if (c < -1) { r[i++] = this.DV + c; }
		r.t = i;
		r.clamp();
	}

	// (protected) this op (1<<n)
	protected changeBit(n: number, op: (a: number, b: number) => number) {
		const r = BigInteger.ONE.shiftLeft(n);
		this.bitwiseTo(r, op, r);
		return r;
	}
	// (protected) true if probably prime (HAC 4.24, Miller-Rabin)
	protected millerRabin(t: number) {
		const n1 = this.subtract(BigInteger.ONE);
		const k = n1.getLowestSetBit();
		if (k <= 0) { return false; }
		const r = n1.shiftRight(k);
		t = (t + 1) >> 1;
		if (t > lowprimes.length) { t = lowprimes.length; }
		const a = nbi();
		for (let i = 0; i < t; ++i) {
			// Pick bases at random, instead of starting at 2
			a.fromInt(lowprimes[Math.floor(Math.random() * lowprimes.length)]);
			let y = a.modPow(r, this);
			if (y.compareTo(BigInteger.ONE) !== 0 && y.compareTo(n1) !== 0) {
				let j = 1;
				while (j++ < k && y.compareTo(n1) !== 0) {
					y = y.modPowInt(2, this);
					if (y.compareTo(BigInteger.ONE) === 0) { return false; }
				}
				if (y.compareTo(n1) !== 0) { return false; }
			}
		}
		return true;
	}
	// (protected) this % n, n < 2^26
	protected modInt(n: number) {
		if (n <= 0) {
			return 0;
		}
		const d = this.DV % n;
		let r = (this.s < 0) ? n - 1 : 0;
		if (this.t > 0) {
			if (d === 0) {
				r = this[0] % n;
			} else {
				for (let i = this.t - 1; i >= 0; --i) {
					r = (d * r + this[i]) % n;
				}
			}
		}
		return r;
	}
	// (protected) r = this op a (bitwise)
	protected bitwiseTo(a: BigInteger, op: (a: number, b: number) => number, r: BigInteger) {
		let i;
		let f;
		const m = Math.min(a.t, this.t);
		for (i = 0; i < m; ++i) {
			r[i] = op(this[i], a[i]);
		}
		if (a.t < this.t) {
			f = a.s & this.DM;
			for (i = m; i < this.t; ++i) {
				r[i] = op(this[i], f);
			}
			r.t = this.t;
		} else {
			f = this.s & this.DM;
			for (i = m; i < a.t; ++i) {
				r[i] = op(f, a[i]);
			}
			r.t = a.t;
		}
		r.s = op(this.s, a.s);
		r.clamp();
	}

	// (protected) this *= n, this >= 0, 1 < n < DV
	protected dMultiply(n: number) {
		this[this.t] = this.am(0, n - 1, this, 0, 0, this.t);
		++this.t;
		this.clamp();
	}
	// (protected) convert from radix string
	protected fromRadix(s: string, b: number | null | undefined) {
		this.fromInt(0);
		if (b == null) {
			b = 10;
		}
		const cs = this.chunkSize(b);
		const d = Math.pow(b, cs);
		let mi = false;
		let j = 0;
		let w = 0;
		for (let i = 0; i < s.length; ++i) {
			const x = intAt(s, i);
			if (x < 0) {
				if (s.charAt(i) === '-' && this.signum() === 0) { mi = true; }
				continue;
			}
			w = b * w + x;
			if (++j >= cs) {
				this.dMultiply(d);
				this.dAddOffset(w, 0);
				j = 0;
				w = 0;
			}
		}
		if (j > 0) {
			this.dMultiply(Math.pow(b, j));
			this.dAddOffset(w, 0);
		}
		if (mi) { BigInteger.ZERO.subTo(this, this); }
	}
	// (protected) return x s.t. r^x < DV
	protected chunkSize(r: number) {
		return Math.floor(Math.LN2 * this.DB / Math.log(r));
	}
	// (protected) convert to radix string
	protected toRadix(b?: number | null) {
		if (b == null) { b = 10; }
		if (this.signum() === 0 || b < 2 || b > 36) { return '0'; }
		const cs = this.chunkSize(b);
		const a = Math.pow(b, cs);
		const d = nbv(a);
		const y = nbi();
		const z = nbi();
		let r = '';
		this.divRemTo(d, y, z);
		while (y.signum() > 0) {
			r = (a + z.intValue()).toString(b).substr(1) + r;
			y.divRemTo(d, y, z);
		}
		return z.intValue().toString(b) + r;
	}

	// (protected) set from string and radix
	protected fromString(s: string, b: 2 | 4 | 8 | 16 | 32 | 256 | number) {
		let k;
		if (b === 16) {
			k = 4;
		} else if (b === 8) {
			k = 3;
		} else if (b === 256) {
			k = 8; // byte array
		} else if (b === 2) {
			k = 1;
		} else if (b === 32) {
			k = 5;
		} else if (b === 4) {
			k = 2;
		} else {
			this.fromRadix(s, b);
			return;
		}
		this.t = 0;
		this.s = 0;
		let i = s.length;
		let mi = false;
		let sh = 0;
		while (--i >= 0) {
			const x = (k === 8) ? (s[i] as any as number) & 0xff : intAt(s, i);
			if (x < 0) {
				if (s.charAt(i) === '-') {
					mi = true;
				}
				continue;
			}
			mi = false;
			if (sh === 0) {
				this[this.t++] = x;
			} else if (sh + k > this.DB) {
				this[this.t - 1] |= (x & ((1 << (this.DB - sh)) - 1)) << sh;
				this[this.t++] = (x >> (this.DB - sh));
			} else {
				this[this.t - 1] |= x << sh;
			}
			sh += k;
			if (sh >= this.DB) {
				sh -= this.DB;
			}
		}
		if (k === 8 && ((s[0] as any as number) & 0x80) !== 0) {
			this.s = -1;
			if (sh > 0) {
				this[this.t - 1] |= ((1 << (this.DB - sh)) - 1) << sh;
			}
		}
		this.clamp();
		if (mi) { BigInteger.ZERO.subTo(this, this); }
	}

	// (protected) alternate constructor
	protected fromNumber(a: number, b: number | SecureRandom, c?: number) {
		if ('number' === typeof b) {
			// new BigInteger(int,int,RNG)
			if (a < 2) {
				this.fromInt(1);
			} else {
				this.fromNumber(a, c!);
				if (!this.testBit(a - 1)) {    // force MSB set
					this.bitwiseTo(BigInteger.ONE.shiftLeft(a - 1), op_or, this);
				}
				if (this.isEven()) {
					this.dAddOffset(1, 0);
				} // force odd
				while (!this.isProbablePrime(b)) {
					this.dAddOffset(2, 0);
					if (this.bitLength() > a) { this.subTo(BigInteger.ONE.shiftLeft(a - 1), this); }
				}
			}
		} else {
			// new BigInteger(int,RNG)
			const x = new Array<number>();
			const t = a & 7;
			x.length = (a >> 3) + 1;
			b.nextBytes(x);
			if (t > 0) {
				x[0] &= ((1 << t) - 1);
			} else {
				x[0] = 0;
			}
			this.fromString(x as any as string, 256);
		}
	}

	// (protected) r = this << n
	protected lShiftTo(n: number, r: BigInteger) {
		const bs = n % this.DB;
		const cbs = this.DB - bs;
		const bm = (1 << cbs) - 1;
		const ds = Math.floor(n / this.DB);
		let c = (this.s << bs) & this.DM;
		let i;
		for (i = this.t - 1; i >= 0; --i) {
			r[i + ds + 1] = (this[i] >> cbs) | c;
			c = (this[i] & bm) << bs;
		}
		for (i = ds - 1; i >= 0; --i) { r[i] = 0; }
		r[ds] = c;
		r.t = this.t + ds + 1;
		r.s = this.s;
		r.clamp();
	}

	// (protected) r = this >> n
	protected rShiftTo(n: number, r: BigInteger) {
		r.s = this.s;
		const ds = Math.floor(n / this.DB);
		if (ds >= this.t) { r.t = 0; return; }
		const bs = n % this.DB;
		const cbs = this.DB - bs;
		const bm = (1 << bs) - 1;
		r[0] = this[ds] >> bs;
		for (let i = ds + 1; i < this.t; ++i) {
			r[i - ds - 1] |= (this[i] & bm) << cbs;
			r[i - ds] = this[i] >> bs;
		}
		if (bs > 0) { r[this.t - ds - 1] |= (this.s & bm) << cbs; }
		r.t = this.t - ds;
		r.clamp();
	}

	// (protected) true iff this is even
	protected isEven() {
		return ((this.t > 0) ? (this[0] & 1) : this.s) === 0;
	}

	// (protected) this^e, e < 2^32, doing sqr and mul with "r" (HAC 14.79)
	protected exp(e: number, z: Classic | Montgomery | NullExp) {
		if (e > 0xffffffff || e < 1) {
			return BigInteger.ONE;
		}
		let r = nbi();
		let r2 = nbi();
		const g = z.convert(this);
		let i = nbits(e) - 1;
		g.copyTo(r);
		while (--i >= 0) {
			z.sqrTo(r, r2);
			if ((e & (1 << i)) > 0) {
				z.mulTo(r2, g, r);
			} else {
				const t = r;
				r = r2;
				r2 = t;
			}
		}
		return z.revert(r);
	}

}

// return new, unset BigInteger
export function nbi() { return new BigInteger(null); }

// Digit conversions
const BI_RM = '0123456789abcdefghijklmnopqrstuvwxyz';
const BI_RC = new Array();
let rr;
let vv;
rr = '0'.charCodeAt(0);
for (vv = 0; vv <= 9; ++vv) {
	BI_RC[rr++] = vv;
}
rr = 'a'.charCodeAt(0);
for (vv = 10; vv < 36; ++vv) {
	BI_RC[rr++] = vv;
}
rr = 'A'.charCodeAt(0);
for (vv = 10; vv < 36; ++vv) {
	BI_RC[rr++] = vv;
}

function int2char(n: number) {
	return BI_RM.charAt(n);
}

function intAt(s: string, i: number) {
	const c = BI_RC[s.charCodeAt(i)];
	return (c == null) ? -1 : c;
}

// return bigint initialized to value
function nbv(i: number) {
	const r = nbi();
	r.fromInt(i);
	return r;
}

// returns bit length of the integer x
function nbits(x: number) {
	let r = 1;
	let t;
	// tslint:disable-next-line:no-conditional-assignment
	if ((t = x >>> 16) !== 0) {
		x = t; r += 16;
	}
	// tslint:disable-next-line:no-conditional-assignment
	if ((t = x >> 8) !== 0) {
		x = t; r += 8;
	}
	// tslint:disable-next-line:no-conditional-assignment
	if ((t = x >> 4) !== 0) {
		x = t; r += 4;
	}
	// tslint:disable-next-line:no-conditional-assignment
	if ((t = x >> 2) !== 0) {
		x = t; r += 2;
	}
	// tslint:disable-next-line:no-conditional-assignment
	if ((t = x >> 1) !== 0) {
		x = t; r += 1;
	}
	return r;
}

function op_and(x: number, y: number) {
	return x & y;
}

function op_or(x: number, y: number) {
	return x | y;
}

function op_xor(x: number, y: number) {
	return x ^ y;
}

function op_andnot(x: number, y: number) {
	return x & ~y;
}

// return index of lowest 1-bit in x, x < 2^31
function lbit(x: number) {
	if (x === 0) {
		return -1;
	}
	let r = 0;
	if ((x & 0xffff) === 0) {
		x >>= 16; r += 16;
	}
	if ((x & 0xff) === 0) {
		x >>= 8; r += 8;
	}
	if ((x & 0xf) === 0) {
		x >>= 4; r += 4;
	}
	if ((x & 3) === 0) {
		x >>= 2; r += 2;
	}
	if ((x & 1) === 0) {
		++r;
	}
	return r;
}

// return number of 1 bits in x
function cbit(x: number) {
	let r = 0;
	while (x !== 0) {
		x &= x - 1; ++r;
	}
	return r;
}
